Exceptions to the temperature–size rule: no Lilliput Effect in end-Permian ostracods (Crustacea) from Aras Valley (northwest Iran)

The body size of marine ectotherms is often negatively correlated with ambient water temperature, as seen in many clades during the hyperthermal crisis of the end-Permian mass extinction (c. 252 Ma). However, in the case of ostracods, size changes during ancient hyperthermal events are rarely quantified. In this study, we evaluate the body size changes of ostracods in the Aras Valley section (northwest Iran) in response to the drastic warming during the end-Permian mass extinction at three taxonomic levels: class, order, species. At the assemblage level, the warming triggers a complete species turnover in the Aras Valley section, with larger, newly emerging species dominating the immediate post-extinction assemblage for a short time. Individual ostracod species and instars do not show dwarfing or a change in body size as an adaptation to the temperature stress during the end-Permian crisis. This may indicate that the ostracods in the Aras Valley section might have been exceptions to the temperature–size rule (TSR), using an adaptation mechanism that does not involve a decrease in body size. This adaptation might be similar to the accelerated development despite constant instar body sizes that can be observed in some recent experimental studies of ostracod responses to thermal stress

Late Glacial to mid Holocene lacustrine ostracods from southern Anatolia, Turkey:A palaeoenvironmental study with pollen and stable isotopes

This study investigates the ostracod assemblages obtained from a sediment core from a paleolake in the Sağlık plain in south-central Anatolia (Turkey). In addition to ostracods, oxygen and. carbon stable isotopes of ostracod shells were analysed and pollen analysis of the core undertaken. The sediments comprise the Late Glacial and early Holocene interval with an approximate 14C age from 18,000 to 6700 14C years ago, after applying a correction for reservoir effects. Eight podocopid ostracod species were recorded, among them Cyprideis torosa and Candona sp. which were used for stable oxygen and carbon isotope analyses. C. torosa dominated during the Late Glacial while Candona sp. dominated most of the early Holocene assemblages. Both forms of C. torosa disappear abruptly close to the onset of the Holocene. Around this time, ostracod preservation was dominated by many black coloured valves and carapaces. Based on ostracod assemblage data and isotope analyses, relatively wet phases were identified for the Older Dryas, Younger Dryas, and during the mid-Holocene at around 7500 14C years ago. Relatively dry phases were identified during the Allerød interstadial, at the end of YD, and at about 6700 14C years ago. An oligotrophic and brackish lake persisted until shortly before the end of the YD, when, according to the δ 13C values, conditions gradually became more eutrophic. The sudden disappearance of C. torosa at the end of the YD seems the consequence of anoxic bottom water conditions and/or eutrophication. Alternating wet and dry phases characterize the early Holocene, with a longer period of wet and oligotrophic conditions around 7500 14C years ago (ca. 8300 calBP). Ostracod assemblages and isotope records indicate a dry and more productive lake around 6700 14C years ago (ca. 7550 calBP)

Two families of non-LTR retrotransposons, Syrinx and Daphne, from the Darwinulid ostracod, Darwinula stevensoni

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Gene 371 (2006): 296-307, doi:10.1016/j.gene.2005.12.007.Two novel families of non-LTR retrotransposons, named Syrinx and Daphne, were cloned and characterized in a putative ancient asexual ostracod Darwinula stevensoni. Phylogenetic analysis reveals that Daphne is the founding member of a novel clade of non-LTR retroelements, which also contains newly described families from the sea urchin and the silkworm and forms a sister clade to L2-like elements. The Syrinx family of non-LTR retrotransposons exhibits evidence of relatively recent activity, manifested in high levels of sequence similarity between individual copies and a three- to ten-fold excess of synonymous substitutions, which is indicative of purifying selection. The Daphne family may have very few copies with intact open reading frames, and exhibits neutral within-family ratio of non-synonymous to synonymous substitutions. It can additionally be characterized by formation of inverted truncated head-to-head structures. All of these features make recent activity less likely than in the Syrinx family. Our results are discussed in light of the evolutionary consequences of long-term asexuality in general and in Darwinula stevensoni in particular.I.S. acknowledges funding from the EC (Marie-Curie grant BIO-4-CT-98-5086) and the Belgian OSTC (MO/36/005), and I.A. would like to thank the U.S. National Science Foundation

First description of the soft part anatomy of Ilyocypris ramirezi Cusminsky & Whatley (Crustacea, Ostracoda) from Argentina, South America

The anatomy of the soft parts of Ilyocypris ramirezi Cusminsky & Whatley, 1996 is described and illustrated for the first time, based on findings of this species from water bodies in the shallow areas of the Llancanelo basin, south-west of Mendoza Province, Argentina. This species is common in Quaternary and extant environments of the Pampa and Patagonian regions. Its distribution is now extending in Argentina to the Central-West area, locally named “Cuyo region”. Ilyocypris ramirezi is a good environmental indicator and constitutes a useful tool in paleolimnological studies.Fil: D'ambrosio, Débora Sabina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Diaz, Analia Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Garcia, Adriana. University Of Wollongong; AustraliaFil: Claps, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

Reevaluation of carbonate concentration and oxygen isotope records from Lake Qinghai, the northeastern Tibetan Plateau

Lake Qinghai is the largest lake on the Tibetan Plateau, and it is also one of the important sites for studying global environmental changes. Over the past 30 years, many studies have used oxygen isotope of authigenic carbonates from the lake as the proxy to infer past environmental and climate changes on the Plateau. However, debate on interpretations of isotopic data and their environmental implications still exist, largely due to the complex arid environment settings and multiple sources/species for carbonate minerals within the lake. In this study, we systematically analyze delta O-18 values in different-type carbonates collected [i.e. bulk carbonates, ostracode shells, Chara encrustations, and fine-grain (< 63 mu m) carbonate minerals] from modern lake sediments and surrounding soils, as well as the down-core delta O-18 values of bulk/fine-grain carbonates since the Last Glacial Maximum. Together with previously published delta O-18 records from ostracode shells, we try to re-evaluate the controlling factors of variations in lacustrine carbonate delta O-18 data and to infer environmental changes on the northeastern Tibetan Plateau since the Last Glacial Maximum. Our results show that the lake depth, or the size of the water body, is an important factor to influence the lake water and carbonate delta O-18 values. A shallow and small lake would be more easily influenced by precipitation delta O-18 which is characterized by negative values at Lake Qinghai region, while a deep and large lake would be better to reflect environmental changes such as the precipitation-evaporation balance. The "lake volume" effect might be an explanation for the negative carbonate delta O-18 values during the early Holocene, which was likely caused by an increased influence of negative delta O-18 values in precipitation and glacial melt water under a small and shallow water body. The delta O-18 values of ostracode shells and bulk carbonates show similar variations since both of them are dominated by lake water oxygen isotopic composition, but they still have distinct geochemical information. The isotopic differences between ostracode and bulk carbonates probably reflect the temperature differences between the surface and the bottom of lake water. In addition, the delta O-18 values of evaporative induced carbonates may correlate with carbonate contents, while those of Chara encrustations do not show any correlation with carbonate contents. Our results suggest that special caution would be necessary when using lacustrine delta O-18 values of authigenic carbonates to infer past hydrological and climate changes in an arid environment

Feeding spectra and activity of the freshwater crab Trichodactylus kensleyi (Decapoda: Brachyura: Trichodactylidae) at La Plata basin

Background: In inland water systems, it is important to characterize the trophic links in order to identify the ‘trophic species’ and, from the studies of functional diversity, understand the dynamics of matter and energy in these environments. The aim of this study is to analyze the natural diet of Trichodactylus kensleyi of subtropical rainforest streams and corroborate the temporal variation in the trophic activity during day hours. Results: A total of 15 major taxonomic groups were recognized in gut contents. The index of relative importance identified the following main prey items in decreasing order of importance: vegetal remains, oligochaetes, chironomid larvae, and algae. A significant difference was found in the amount of full stomachs during day hours showing a less trophic activity at midday and afternoon. The index of relative importance values evidenced the consumption of different prey according to day moments. Results of the gut content indicate that T. kensleyi is an omnivorous crab like other trichodactylid species. Opportunistic behavior is revealed by the ingestion of organisms abundant in streams such as oligochaetes and chironomid larvae. The consumption of allochthonous plant debris shows the importance of this crab as shredder in subtropical streams. However, the effective assimilation of plant matter is yet unknown in trichodactylid crabs. Conclusions: This research provides knowledge that complements previous studies about trophic relationships of trichodactylid crabs and supported the importance of T. kensleyi in the transference of energy and matter from benthic community and riparian sources to superior trophic levels using both macro- and microfauna.Fil: Williner, Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: de Azevedo Carvalho, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Collins, Pablo Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentin

Paleoenvironmental Reconstruction of Quaternary Saltville, Virginia, using Ostracode Autecology

The Saltville valley in southwestern Virginia is home to Quaternary localities containing paleontological and archaeological remains. Historically the valley has been mined for salt and the small lakes, ponds and springs along the valley floor have a brackish signature. A preliminary report on the site’s ostracode fauna suggested that the site’s water was not always saline. This study analyzed modern and Quaternary ostracodes to understand the valley’s hydrologic and chemical evolution. Sediments contained primarily freshwater species, including the environmentally sensitive Candona crogmaniana. The presence of Pelocypris tuberculatum and a new Fabaeformiscandona species throughout a vertical section spanning the latest Pleistocene and Holocene suggests that ephemeral pools were being fed by freshwater springs throughout the latest Quaternary. Climate ranges, estimated through species autecology and MOTR, reveal that the site’s mean annual temperature was between 0 - 19.1℃. Ostracode salinity tolerances suggest that the site was fresh during the sampled record

Geochemical and ecological aspects of lower Frasnian pyrite-ammonoid level at Kostomłoty (Holy Cross Mountains, Poland)

The lower Frasnian (transitans Zone with Ancyrodella priamosica = MN 4 Zone) rhythmic basin succession of marly limestones and shales (upper Szydlówek Beds) at Kostomloty, western Holy CrossMts., Central Poland, contains a record of the transgressive-hypoxic Timan Event in this drowned part of southern Laurussian shelf. The unique facies consists of organic-rich marly shales and a distinctive pyritic, goniatite level, 1.6m thick. The faunal assemblage is dominated by pyritized shells of diminutivemollusks with cephalopods (including goniatites Epitornoceras and Acanthoclymenia), buchioline bivalves (Glyptohallicardia) and styliolinids. This interval is marked by moderately low Th/U ratios and pyrite framboid size distributions suggestive of dysoxic rather than permanent euxinic conditions. The scarcity of infauna and bioturbation resulted in finely laminated sedimentary fabrics, as well as the low diversity of the presumed pioneer benthos (mostly brachiopods). In the topmost part of the Szydlówek Beds, distinguished by the Styliolina coquina interbedded between limestone-biodetrital layers, the above geochemical proxies and C-isotope positive shift indicate a tendency to somewhat increased bottom oxygen deficiency and higher carbon burial rate linked with a bloom of pelagic biota during high-productivity pulse. The geochemical and community changes are a complex regional record of the initial phase of a major perturbation in the earth-ocean system during a phase of intermittently rising sea level in the early to middle Frasnian, and associated with the highest positive C-isotope ratios of the Devonian

Size variations in foraminifers from the early Permian to the Late Triassic: Implications for the Guadalupian-Lopingian and the Permian-Triassic mass extinctions

The final 10 Myr of the Paleozoic saw two of the biggest biological crises in Earth history: the middlePermian extinction (often termed the Guadalupian–Lopingian extinction [GLE]) that was followed 7–8 Myr later by Earth's most catastrophic loss of diversity, the Permian–Triassic mass extinction (PTME). These crises are not only manifest as sharp decreases in biodiversity and—particularly for the PTME—total ecosystem collapse, but they also drove major changes in biological morphological characteristics such as the Lilliput effect. The evolution of test size among different clades of foraminifera during these two extinction events has been less studied. We analyzed a global database of foraminiferal test size (volume) including 20,226 specimens in 464 genera, 98 families, and 9 suborders from 632 publications. Our analyses reveal significant reductions in foraminiferal mean test size across the Guadalupian/Lopingian boundary (GLB) and the Permian/Triassic boundary (PTB), from 8.89 to 7.60 log10 μm3 (lg μm3) and from 7.25 to 5.82 lg μm3, respectively. The decline in test size across the GLB is a function of preferential extinction of genera exhibiting gigantism such as fusulinoidean fusulinids. Other clades show little change in size across the GLB. In contrast, all Lopingian suborders in our analysis (Fusulinina, Lagenina, Miliolina, and Textulariina) experienced a significant decrease in test size across the PTB, mainly due to size-biased extinction and within-lineage change. The PTME was clearly a major catastrophe that affected many groups simultaneously, and the GLE was more selective, perhaps hinting at a subtler, less extreme driver than the later PTME